Spot‐scanning hadron arc (SHArc) therapy: A proof of concept using single‐ and multi‐ion strategies with helium, carbon, oxygen, and neon ions

Abstract

Purpose To present particle arc therapy treatments using single and multi‐ion therapy optimization strategies with helium (4He), carbon (12C), oxygen (16O), and neon (20Ne) ion beams. Methods and materials An optimization procedure and workflow were devised for spot‐scanning hadron arc therapy (SHArc) treatment planning in the PRECISE (PaRticle thErapy using single and Combined Ion optimization StratEgies) treatment planning system (TPS). Physical and biological beam models were developed for helium, carbon, oxygen, and neon ions via FLUKA MC simulation. SHArc treatments were optimized using both single‐ion (12C, 16O, or 20Ne) and multi‐ion therapy (16O+4He or 20Ne+4He) applying variable relative biological effectiveness (RBE) modeling using a modified microdosimetric kinetic model (mMKM) with (α/β)x values of 2, 5, and 3.1 Gy, respectively, for glioblastoma, pancreatic adenocarcinoma, and prostate adenocarcinoma patient cases. Dose, effective dose, linear energy transfer (LET), and RBE were computed with the GPU‐accelerated dose engine FRoG and dosimetric/biophysical attributes were evaluated in the context of conventional particle and photon‐based therapies (e.g., volumetric modulated arc therapy [VMAT]). Results All SHArc plans met the target optimization goals (3GyRBE) and demonstrated increased target conformity and substantially lower low‐dose bath to surrounding normal tissues than VMAT. SHArc plans using a singleion species (12C, 16O, or 20Ne) exhibited favorable LET distributions with the highest‐LET components centralized in the target volume, with values ranging from ∼80–170 keV/μm, ∼130–220 keV/μm, and ∼180–350 keV/μm for 12C, 16O, or 20Ne, respectively, exceeding mean target LET of conventional particle therapy (12C:∼55, 16O:∼75 20Ne:∼95 keV/μm). Multi‐ion therapy with SHArc delivery (SHArcMIT) provided a similar level of target LET enhancement as SHArc compared to conventional planning, however, with additional benefits of homogenous physical dose and RBE distributions. Conclusion Here, we demonstrate that arc delivery of light and heavy ion beams, using either a single‐ion species (12C, 16O, or 20Ne) or combining two ions in a single fraction (16O+4He or 20Ne+4He) affords enhanced physical and biological distributions (e.g., LET) compared with conventional delivery with photons or particle beams. SHArc marks the first single‐ and multi‐ion arc therapy treatment optimization approach using light and heavy ions.

Development and benchmarking of the first fast Monte Carlo engine for helium ion beam dose calculation: MonteRay

“…Qin et al 39 have previously shown that accurate carbon ion dose calculation based on nuclear interaction databases extracted from GEANT are possible. Further work on MonteRay will intend to see how using FLUKA databases performs, especially since de Simoni et al 27 .…”

“…Having the capability of simulating helium ions, MonteRay can serve as a fast and accessible tool for ongoing and future research projects, starting with the upcoming clinical trial using helium ions at HIT as well as foreseen helium ion FLASH investigation, helium ion spot‐scanning hadron arc therapy 39,40 or, with a possible extension towards carbon ions in mind, multi‐ion therapy 41,42 …”

“…Qin et al 39 have previously shown that accurate carbon ion dose calculation based on nuclear interaction databases extracted from GEANT are possible. Further work on MonteRay will intend to see how using FLUKA databases performs, especially since de Simoni et al 27 recently reported on their implementation of carbon ion inelastic nuclear interactions based on a phenomenological model, also achieving accurate dose predictions.…”

“…Having the capability of simulating helium ions, Mon-teRay can serve as a fast and accessible tool for ongoing and future research projects, starting with the upcoming clinical trial using helium ions at HIT as well as foreseen helium ion FLASH investigation, helium ion spot-scanning hadron arc therapy 39,40 or, with a possible extension towards carbon ions in mind, multi-ion therapy. 41,42 The inclusion of carbon ions in MonteRay is expected soon, as the modern C++ codebase and reuse of the successful database driven approach for modeling nuclear interactions will speed up the process.…”

Partitioning of discrete proton arcs into interlaced subplans can bring proton arc advances to existing proton facilities

“…Light ion arcs with single or multi-ions could substantially reduce dose to normal tissue as well as focus high LET into the target. 30,31 However, there are still challenges on the delivery side, which could be remedied by partitioned discrete ion arcs. In a multi-ion setting, the method could potentially be adopted to use different ions in different fractions.…”